docs: def sql_cell(args, cell):
    """Implements the SQL cell magic for ipython notebooks.
  
    The supported syntax is:
  
        %%sql [--module <modulename>]
        [<optional Python code for default argument values>]
        [<optional named queries>]
        [<optional unnamed query>]
  
    At least one query should be present. Named queries should start with:
  
        DEFINE QUERY <name>
  
    on a line by itself.
  
    Args:
      args: the optional arguments following '%%sql'.
      cell: the contents of the cell; Python code for arguments followed by SQL queries.
    """
    name = args['module'] if args['module'] else '_sql_cell'
    module = imp.new_module(name)
    query = _split_cell(cell, module)
    ipy = IPython.get_ipython()
    if not args['module']:
        # Execute now
        if query:
          return datalab.bigquery.Query(query, values=ipy.user_ns) \
            .execute(dialect=args['dialect'], billing_tier=args['billing']).results
    else:
      # Add it as a module
      sys.modules[name] = module
      exec('import %s' % name, ipy.user_ns)